31 ago. 2008

Harnessing the Sun

In the ancient Egyptian city of Cocodrilopolis, lived the Petsuchi, crocodiles adored as gods, adored with jewelry and goldware. They were called the "Sons of Sobek", Sobek being the Crocodile god of the Egyptians. In the video game Age of Mythology, Petsuchi are gigantic crocs that use a burning glass to obliterate armies.

The burning glass is a large (in some cases very large) convex lens used to concentrate the light of the sun in a very small area, thus heating this area, and eventually, burning it (think of a child with a magnifying glass).

The burning glass technology has been known since antiquity. You may remember from an earlier post, i wrote about the Nimrud lens, the oldest known lens, a piece of rock crystal that may have been used as a burning glass.

The most well known use of a burning glass comes from the legend that Archimedes, the greek philosopher, designed and created a gigantic burning glass during the siege of Syracuse. Some people dissent form this belief, saying that it wasn't a burning glass, but a series of mirrors.

One present use of Burning glasses are the solar furnaces used in smart homes and at certain isolated populations of Andine Peru. This use a set of mirrors placed parabolically to concentrate the sun's light on an object, sometime passing through a lens to further condensate the beams.